An artillery projectile or shell is known whose bursting charge is fired by a detonator that is itself activated by an electric charge. This detonator lies at the rear of the shell within the bursting charge. An impact fuze at the nose of the shell is connected to this detonator and serves to electrically activate it whenever the nose of the shell impacts something with a force exceeding a predetermined minimum.
The impact fuze usually has a piezoelectric crystal which is squeezed or crushed when the shell impacts an object and generates an electrical current. A usually copper wire screwed or soldered to this crystal or to an element carrying this crystal is insulated and extends back through the bursting charge to the detonator to carry the electrical current back to this detonator.
When such a projectile is fired with standard muzzle velocity the fuze can be counted on to operate perfectly so long as a relatively hard object is struck by the projectile. When, however, a high muzzle velocity is employed the wire frequently becomes disconnected, so that the fuze cannot operate and the projectile will not explode. Furthermore when a relatively soft object is struck the wire often works loose from the fuze and again renders the projectile nonexplosive.